Mechanical Engineering Interview Questions and Answers
This article will give you the list of subject specific questions frequently asked during mechanical engineering interview. For Personal profile related and experience related questions refer General engineering interview questions.
Mechanical engineering is a branch of engineering that deals with design and manufacturing of machines, machine parts, automobiles, rotating machinery, etc., and maintenance of the above. Mechanical engineers also work on software for design purposes. A mechanical engineering interview would include questions from statics, dynamics, thermodynamics, heat transfer, fluid mechanics, machine design and material sciences.
- Explain the second law of thermodynamics.
The entropy of the universe increases over time and moves towards a maximum value.
- How do you measure temperature in a wet bulb thermometer?
Wet bulb temperature is measured in a wet bulb thermometer by covering the bulb with a wick and wetting it with water. It corresponds to the dew point temperature and relative humidity.
- What is bending moment?
When a moment is applied to bend an element, a bending moment exists in the element
- What are the points in the stress strain curve for steel?
Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.
- Define Reynolds number.
Reynolds number is the ratio of inertial force and viscous force. It is a dimensionless number. It determines the type of fluid flow.
- What is a Newtonian fluid?
A Newtonian fluid possesses a linear stress strain relationship curve and it passes through the origin. The fluid properties of a Newtonian fluid do not change when any force acts upon it.
- How many joules is 1 BTU?
1 BTU is equal to 1055.056 joules.
- What is PS?
PS is Pferdestarke, the German unit for Horsepower.
- Explain Otto cycle.
Otto cycle can be explained by a pressure volume relationship diagram. It shows the functioning cycle of a four stroke engine. The cycle starts with an intake stroke, closing the intake and moving to the compression stroke, starting of combustion, power stroke, heat exchange stroke where heat is rejected and the exhaust stroke. It was designed by Nicolas Otto, a German engineer.
- Explain the nomenclature of a 6203-ZZ bearing.
6 is the type code, which shows it is a single-row ball bearing, 2 is the series, means light, 03 is the bore, which is 17 mm and ZZ is the suffix meaning double shielded bearing.
- What is gear ratio?
It is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.
- What is annealing?
It is a process of heating a material above the re-crystallization temperature and cooling after a specific time interval. This increases the hardness and strength if the material.
- Define torque.
Torque is defined as a force applied to an object that results in rotational motion.
- What is ductile-brittle transition temperature?
It is the temperature below which the tendency of a material to fracture increases rather than forming. Below this temperature the material loses its ductility. It is also called Nil Ductility Temperature.